Gold-mediated synthesis of α-ionone

Merlini, Valentina; Gaillard, Sylvain; Porta, Alessio; Zanoni, Giuseppe; Vidari, Giovanni; Nolan, Steven P.

doi:10.1016/j.tetlet.2011.01.010

Cited by 29 publications

(14 citation statements)

References 37 publications

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“…Ester 23 was then subjected to the gold‐mediated Meyer–Schuster‐like rearrangement under the conditions that we optimized for the synthesis of α‐ionone,12e namely, 2 mol % of the dinuclear gold complex [{Au(IPr)} 2 (μ‐OH)][BF 4 ] (IPr=1,3‐bis(2,6‐ diisopropylphenyl)imidazol‐2‐ylidene) 25 ,17 in a mixture of butan‐2‐one‐H 2 O, 100:1, at 60 °C for 12 h.…”

Section: Resultsmentioning

confidence: 99%

“…The olefin photoisomerization protocol11 proved, indeed, to be much simpler than an alternative multistep route previously employed to move the α‐double bond to the γ‐position 9d. 11 Moreover, a recent synthesis of ( S )‐α‐ionone ( S )‐ 1 ,12e suggested that the [(NHC)Au I ]‐catalyzed13 Meyer–Schuster‐like rearrangement of a propargylic ester12, 14 in an aqueous medium is an attractive alternative to the classical Horner–Wadsworth–Emmons reaction to build the α,β‐enone side‐chain of 7 8 and 8 9c,e. This new method, further preserving the stereochemical integrity at C6, exhibits other remarkable synthetic advantages, such as good atom economy, nontoxicity of the solvent, and the small amount of the catalyst employed.…”

Section: Introductionmentioning

confidence: 99%

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Competitive Gold‐Promoted Meyer–Schuster and oxy‐Cope Rearrangements of 3‐Acyloxy‐1,5‐enynes: Selective Catalysis for the Synthesis of (+)‐(S)‐γ‐Ionone and (−)‐(2S,6 R)‐cis‐γ‐Irone

Bugoni

Merlini

Porta

et al. 2015

Chemistry A European J

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We report a simple, highly stereoselective synthesis of (+)-(S)-γ-ionone and (-)-(2S,6R)-cis-γ-irone, two characteristic and precious odorants; the latter compound is a constituent of the essential oil obtained from iris rhizomes. Of general interest in this approach are the photoisomerization of an endo trisubstituted cyclohexene double bond to an exo vinyl group and the installation of the enone side chain through a [(NHC)Au(I)]-catalyzed Meyer-Schuster-like rearrangement. This required a careful investigation of the mechanism of the gold-catalyzed reaction and a judicious selection of reaction conditions. In fact, it was found that the Meyer-Schuster reaction may compete with the oxy-Cope rearrangement. Gold-based catalytic systems can promote either reaction selectively. In the present system, the mononuclear gold complex [Au(IPr)Cl], in combination with the silver salt AgSbF6 in 100:1 butan-2-one/H2O, proved to efficiently promote the Meyer-Schuster rearrangement of propargylic benzoates, whereas the digold catalyst [{Au(IPr)}2(μ-OH)][BF4] in anhydrous dichloromethane selectively promoted the oxy-Cope rearrangement of propargylic alcohols.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Competitive Gold‐Promoted Meyer–Schuster and oxy‐Cope Rearrangements of 3‐Acyloxy‐1,5‐enynes: Selective Catalysis for the Synthesis of (+)‐(S)‐γ‐Ionone and (−)‐(2S,6 R)‐cis‐γ‐Irone

Bugoni

Merlini

Porta

et al. 2015

Chemistry A European J

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“…Based on these procedures, Nolan and coworkers reported the synthesis of ( E )‐α‐ionone, a norterpenoids α,β‐unsaturated ketone, which is an important fragrance used in the perfume industry for its violet scent . Precursor 48 was engaged in a Meyer‐Schuster‐like rearrangement relying on the intermediate formation of allenylester 49 .…”

Section: 3‐migrationmentioning

confidence: 99%

Gold‐Catalyzed Migration of Propargyl Acetate as an Entry into the Total Synthesis of Natural Products

Fensterbank

2018

Israel Journal of Chemistry

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Gold catalysis has emerged over the last two decades as a protocole of choice for the efficient and selective activation of a variety of organic functional groups. This has served to the total synthesis of natural products at several occasions. In this context, the gold‐catalyzed migration (1,2‐ or 1,3‐) of propargyl acetates has been particularly used. This review highlights these different synthetic developments which are presented according to the involved mechanisms.

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“…[7b] To circumvent this problem, a few years ago we resorted to an alternative methodology based upon a Julia-Lythgoe olefination, although the synthetic sequence was significantly length- Table 3. [25] To extend this procedure also to the synthesis of a-irone, we oxidized alcohol 17 with SIBX [14] to the highly epimerizable aldehyde 44, which, without purification, was immediately submitted to the addition of propynylmagnesium bromide in THF. [ ened.…”

Section: Final Steps Of the Syntheses Of (à)-A-irone 4 And (à)-G-ironementioning

confidence: 99%

“…[8] More recently, we introduced an innovative methodology involving an NHCÀAu I (NHC = N-heterocyclic carbene) catalyzed Meyer-Schuster-like rearrangement of propargylic esters, [24] which was readily employed for the synthesis of the enone moiety of a-ionone. [25] To extend this procedure also to the synthesis of a-irone, we oxidized alcohol 17 with SIBX [14] to the highly epimerizable aldehyde 44, which, without purification, was immediately submitted to the addition of propynylmagnesium bromide in THF. Quenching the resulting alkoxy derivative with benzoyl chloride (BzCl), in the presence of a catalytic amount of 4-dimethylaminopyridine (DMAP), produced propargyl benzoate 45 in 63 % yield (see the Supporting Information for the detailed procedure).…”

Section: Final Steps Of the Syntheses Of (à)-A-irone 4 And (à)-G-ironementioning

confidence: 99%

Enantioselective Divergent Synthesis of (−)‐cis‐α‐ and (−)‐cis‐γ‐Irone by Using Wilkinson’s Catalyst

Bugoni

Boccato

Porta

et al. 2014

Chemistry A European J

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A simple, efficient synthesis is reported for (-)-cis-α- and (-)-cis-γ-irone, two precious constituents of iris oils, in ≥99 % diastereomeric and enantioselective ratios. The two routes diverge from a common intermediate prepared from (-)-epoxygeraniol. Of general interest in this approach is the installation of the enone moiety of irones through a NHCAu(I) -catalyzed Meyer-Schuster-like rearrangement of a propargylic benzoate and the use of Wilkinson's catalyst for the stereoselective hydrogenation of a prostereogenic exocyclic double bond to secure the critical cis stereochemistry of the alkyl groups at C2 and C6 of the irones. The stereochemical aspects of this reaction are rationally supported by DFT calculation of the conformers of the substrates undergoing the hydrogenation and by a modeling study of the geometry of the rhodium η(2) complexes involved in the diastereodifferentiation of the double bond faces. Thus, computational investigation of the η(2) intermediates formed in the catalytic cycle of prostereogenic alkene hydrogenation by using Wilkinson's catalyst could be highly predictive of the stereochemistry of the products.

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Gold-mediated synthesis of α-ionone

Cited by 29 publications

References 37 publications

Competitive Gold‐Promoted Meyer–Schuster and oxy‐Cope Rearrangements of 3‐Acyloxy‐1,5‐enynes: Selective Catalysis for the Synthesis of (+)‐(S)‐γ‐Ionone and (−)‐(2S,6 R)‐cis‐γ‐Irone

Competitive Gold‐Promoted Meyer–Schuster and oxy‐Cope Rearrangements of 3‐Acyloxy‐1,5‐enynes: Selective Catalysis for the Synthesis of (+)‐(S)‐γ‐Ionone and (−)‐(2S,6 R)‐cis‐γ‐Irone

Gold‐Catalyzed Migration of Propargyl Acetate as an Entry into the Total Synthesis of Natural Products

Enantioselective Divergent Synthesis of (−)‐cis‐α‐ and (−)‐cis‐γ‐Irone by Using Wilkinson’s Catalyst

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